1. Field of the Invention
The invention relates to a micro lens, and more particularly to a micro lens suitable for installation in a portable electronic device.
2. Description of the Related Art
With the progress of the technical skills, portable electronic devices such as notebook computers, mobile phones or personal digital assistants incorporating electro-optical technologies have proliferated. A mobile phone with camera, for example, offers high-resolution optics, and is lightweight and inexpensive.
A spherical lens is typically used in a camera, however, optical defects such as spherical image aberration and axial diffraction cause blurry images and out of focus images, thus additional lenses are provided for compensating image aberration. Traditionally, image quality can be improved by increasing the length, outer diameter, weight and cost of the lens, however, the total weight and cost of the camera are relatively increased. Clumsy and heavy lens are no longer a trend in the present market.
To attain a small camera with low manufacturing cost, the total length of the lens must be reduced. An aspherical lens can overcome spherical image aberration caused by a spherical lens. Further, a single aspherical lens can compensate for spherical image aberration requiring several spherical lenses. Thus, the size, weight and optical design of the lens can be simplified.
spherical and aspherical lenses can be made of glass and plastic. A glass lens typically provides a greater light-transmission coefficient and a better image quality than plastic. Glass and plastic lenses are assembled to form a desired lens based on material characteristics.
Current mobile phones typically employ glass and plastic lenses such as 1G(glass)2P(plastic) or 1G3P. U.S. Pat. No. 6,441,971 discloses a compact lens assembly related to 1G2P. From an object side to an image side, the compact lens assembly sequentially comprises a first lens element, a second lens element and a third lens element. The first lens element is a glass spherical lens, and the second and third lens elements are plastic aspherical lenses. The compact lens assembly is tiny and only suitable for an image sensor having a resolution of about 640×480 pixels. Although the 1G3P lens can provide good resolution, the weight and cost of the 1G3P is still high.